I haven’t come up with rules for how a player character can create their own faction, and it’s possible they either can’t, or shouldn’t. What makes more sense is for the PCs to join an affiliation, work their way up through the ranks, and eventually remake the affiliation in their own image. It rewards them with an affiliation that has deep ties to the community, and some real history (not to mention baggage).

To increase a faction’s scale at Local scope, you have to gain an audience with the ruling body and negotiate the completion of new roads and settlements. If the active faction has the Resources required to purchase a Development Card (which costs one sheep, one grain, and one ore), they will, because they desire to expand their military at the expense of infrastructure.

Each knight added to a Local faction increases its scale by one (and therefore the level of Challenges to interact with the faction) and will likely impose a penalty to the affiliation score of any adventurers who are also members, regardless of rank within the faction — even if the adventurers are the leaders of said faction. Knights cause problems for everyone, though they still do carry certain benefits.

Important to note is that all factions begin as slave factions, basically amounting to small agrarian communities not all that much different from primitive tribes. Once they reach the point where they have at least three knights, or five roads (when either the Largest Army or Longest Road are first awarded) they change to a prince faction.

Local Faction scale:
* Number of “plus one” Development Cards
* Number of knights
* Number of roads
* Number of cities and towns(add an additional one for each city)

…Just as I was putting the finishing touches on a PDF chart, it occurred to me there might be additional rules in the expansions for The Settlers of Catan that could be useful in calculating this stuff. I figured it would be a good idea to take a look at the rulebooks they have online and see if there’s anything else worth adding.